1. Field of the Invention
The invention relates to a video signal processing apparatus applicable to a manually induced vibration correction device for video data such as an output produced by a hand-held type video camera.
2. Description of the Prior Art
When a picture is taken using a portable hand-held or so called "handy" type video camera, there is a problem that the reproduced picture jumps about or vibrates due to vibration caused by manual manipulation of the device. To solve this problem, a technique where a motion vector is detected and video data stored in a picture memory is then corrected based on this motion vector, has been proposed (for example, Japanese Patent Disclosure Sho 63-166370). The detection of the motion vector is achieved using block matching, for instance. With this technique, a picture is divided into many areas (called "blocks"), an absolute value of a frame difference between a representative point of a previous frame lying at a central portion of each block and picture element data within a block of the present frame is calculated, an absolute value of a frame difference is accumulated with respect to one picture, and the motion vector is detected from the position of a minimum value of accumulated frame difference data. Also, as described in this publication, picture enlargement to the extent of 15%, for example, is carried out by read-out control of the picture memory, interpolation circuit is used to prevent video data from being lost when the motion correction is made. For such a manually induced vibration correction device, accurate detection of the manually induced vibration is required.
Enlargement of a picture is executed by a process which delays the read-out speed of a picture memory as compared with its write-in speed and which interpolates deficient picture element data. The picture enlargement consequently causes deterioration such as blurring as compared with the original picture.